When making a phone call in the conventional voice communication service, a caller will only hear monotonous bell rings before the call is picked up. After a Ring Back Tone (RBT) service came into the market, according to the RBTs customized by the called terminal, the caller may hear music, songs, stories, dialogues, etc., instead of the monotonous bell rings, which largely increases the customer's experience satisfaction.
The implementation of RBT service in the prior art is comparatively complex, in which the existing communication devices on the network side need to be improved and some new communication devices need to be added to the network side, for instance, a Home Location Register (HLR) and a Mobile Switching Center (MSC) need to be improved and a RBT Server (RBTS) needs to be added. Moreover, the system has to manage multiple communication devices working in collaboration, which makes the information interaction rather complex as well, and it is especially far from fully satisfying the users' demand for customization that the RBTs are usually provided by content providers currently so that the user may choose among limited types and quantities of RBTs provided at the designated locations.